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[ferret_users] Query about mp_polygon



Hello all,

I'm trying to draw a polygon on a mp_stereographic_south projected map
(Antarctica). I searched for the mp_polygon command on-line and see it
is referenced in the v54 manual, but it is not referenced in the v6.6.2
version (I'm still running v6.2; mp_polygon doesn't exist in the go
directory either). Is it missing from the later installations or has it
been retired? If retired, how can I plot polygons on a projected map.

Actually what I am trying to do is a bit of a hack and am wondering if
someone knows of a better way. 

Conceptually, I want to draw a 400km x 500km box around a number of
lat/lon site locations and work out the amount of area that they cover
in relation to the total area. 

The method I have come up with to solve this, is to define a region with
the approx correct dimensions, find the area of the region, save the
data and sum it all up outside of ferret. This limits my solution
because I can only have a xmin:xmax/ymin:ymax shape region and I don't
know how to computationally account for overlap in the regions, if there
is any. I know you can define a variable region based on a variable
threshold, but the I have no variable to define my 400km x 00km box,
just dimensions.

The reason I want mp_polygon is to visualise the regions in relation to
my full extent, i.e Antarctica. What would be ideal, if I could plot
them, would be to find the total area of all my polygons.

Hope someone can help. 

Rob




-----------------------------------------------
Ph.D candidate Glacial Systems Dynamics

Department of Physics and Physical Oceanography
Memorial University of Newfoundland, St. John's




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